The present invention relates generally to medical apparatus and methods, and more particularly, to devices and methods for percutaneous removal of unwanted tissue such as thrombus, atheroma, fluid, polyps, cysts or other obstructive matter from body lumens, such as blood vessels, ureters, bile ducts or fallopian tubes. More specifically, the present invention relates to the excision of the thickened atheromatous tunica intima of an artery, a procedure known as an endarterectomy.
An endarterectomy is a surgical procedure that removes material involved in a narrowing or blockage of an artery. Typically, such a procedure is performed on the carotid arteries where atheromatous material or plaque has narrowed or occluded the carotid arteries reducing the supply of blood flow to the brain. Untreated, this may lead to neurological deficits and stroke. Deficits can occur due to a decrease in oxygen-rich blood to the brain causing destruction of brain tissue. Strokes can occur due to uncontrolled blood pressure or bursting of weakened blood vessels in the brain. The risk of both of these conditions can be reduced by carotid endarterectomy.
A typical endarterectomy procedure is illustrated in FIGS. 1A-1C. FIG. 1A is a cross-sectional view of a blood vessel BV prior to treatment. As shown, the wall of the blood vessel BV is comprised of two layers, an intimal layer INT or inner-most layer of the lumen which is in contact with the blood and an adventitial layer ADV or outer layer which is covered by the intimal layer INT. In this case, the blood vessel BV is narrowed or partially blocked by occlusive material or an occlusion OC. Blood flowing through the vessel is restricted through the area of the occlusion OC as illustrated by arrows. It should be noted that the term occlusion OC might refer to any substance or anatomic morphology that acts to severely occlude a body conduit such that it is difficult to pass a wire from proximal end of the occlusion to the distal end. Depending on the type of material occluding the body conduit (soft plaque, calcified plaque, thrombus, fibrin, clot, fatty tissue etc.) some occlusions may be more severe than others but all are included in the scope of the present invention when there may be some difficulty passing a guidewire therethrough.
Referring to FIG. 1B, an endarterectomy procedure may involve removing the occlusion OC along with the intimal layer INT in the region of the occlusion. Here, the intimal layer INT is cut, split or cleaved to access the adventitial layer ADV. The intimal layer INT is then pulled away, stripped or delaminated from the adventitial layer ADV along the length of the occlusion OC. Referring to FIG. 1C, the intimal layer INT is also cleaved on the opposite side of the occlusion OC to remove the delaminated intimal layer INT containing the occlusion OC from the vessel wall. The excised material may then be removed from the blood vessel BV. It may be appreciated that the above described procedure may be readily adapted for use in any body lumen or body cavity wherein unwanted material may be removed in a similar fashion.
Currently, there are many clinical approaches to removing unwanted material, many of which are performed surgically, wherein the treatment site is accessed directly through a surgical incision. An example of this surgical procedure utilizes a set of surgical tools, like The MollRing Cutter™, which enable the surgeon to cleave a plane of an occluded vessel and strip the atheromatous intimal layer, such as described in U.S. Pat. Nos. 5,843,102 and 5,954,713.
In recent years, a variety of catheter devices have been developed for use in intraluminal and intravascular procedures for fragmentation and removal of blood clots, or thrombus, from blood vessels. More recently, devices that can be inserted percutaneously through a puncture in the skin have been developed to make the procedures less invasive. For example, a catheter device is inserted into a blood vessel at some distance away from the intended treatment site, and is then advanced through the vessel lumen until the selected location is reached. In many cases the vessel to be treated is totally blocked by an occlusive lesion usually comprising, thrombus, soft plaque, and calcified plaque.
Several techniques have been introduced to fragment the unwanted plaque or tissue from blood vessels such as rotating baskets or impellers as described in U.S. Pat. Nos. 5,766,191 and 5,569,275, cutters U.S. Pat. No. 5,501,694, or high pressure fluid infusion to create a Venturi effect as described in U.S. Pat. No. 5,795,322. Other devices, such as atherectomy cutters, may also be employed such as those described in U.S. Pat. Nos. 5,904,968, 5,224,945, 5,312,425 and 5,330,484.
In many instances, these techniques further include aspirating the unwanted occlusive materials through a lumen of the treatment device or using a secondary catheter hooked up to a source of vacuum/suction. Critical to the success of an improved procedure is having a device that can rapidly aspirate the occlusive material from the body lumen. One such device is described in U.S. patent application Ser. No. 09/454,517 and in U.S. Provisional Application No. 60/154,752.
Although these techniques provide many benefits, it is also desired to provide some of the benefits of traditional endarterectomy in intraluminal and intravascular procedures. In particular, it would be desired to percutaneously treat a total occlusion using a set of tools that perform similar functions to those performed in traditional surgical endarterectomy procedures. These tools would first provide a cleavage plane circumferentially or longitudinally of the lesion, dissect the cylindrical core, macerate the core, and aspirate the material. Thus, it would be desirable to provides devices, systems, methods and kits to this end. At least some of these objectives will be met by the aspects of the present invention.